The invention under consideration concerns a device for the production of corrugated pipes from thermoplastic, in which supplementary mold jaws, in pairs, are jointly conducted in a cycle along a mold section leading away from an extruder head; they are moved apart at the end of the mold section; and they are returned to their beginning separately from one another with a mold section device to move the mold jaws along the mold section, which has a supporting table with drive means for the mold jaws on the mold section, and with a return conveyance to return the mold jaws from the end of the mold section to its beginning, which has an outlet assembly to move apart the mold jaws at the end of the mold section and/or an inlet assembly to move in the mold jaws at the beginning of the mold section.
With those corrugated pipe units of the so-called shuttle type, return conveyors that move back and forth are used. The return conveyors can have a gripping arm, which grips a mold jaw, found at the end of the mold section, moves to the beginning of the mold section, puts down the mold jaw there, and joins or attaches it to the mold jaw that is moving in front, and subsequently again moves to the end of the mold section so as to grip there the next mold jaw. On the mold section itself, the mold jaws are moved on by separate drives, which, on the one hand, lie on the supporting table, and on the other hand, are located on the cover frame lying above. In particular, the provision of drive pinions in the supporting table and in the cover frame lying above is known; they mesh in the toothed racks located on the mold jaws, above and below, and move them correspondingly forwards.
EP-A-0 764 516 discloses a device for the production of pipes from thermoplastic with transverse profiling, which has mold jaws in pairs conducted in a cycle on a mold section. A transporting device for the return of the mold jaws is provided, and is designed like abridge crane. Two transport conveyances, which can be moved transverse to the production direction and in directions opposite one another, are provided on the transport bridge that overlaps the mold section; a transport arm, directed downwards and with a holding device, is affixed on these conveyances, one for each mold jaw.
From WO-A-94 07673, also, a corrugated pipe unit is known in which the pair of mold jaws are comprised in two groups. A first group is supported on a carriage that can be moved back and forth on a lower carrying frame. A second group of mold jaws is supported on a carriage that can be moved back and forth on an upper carrying frame of a bridge crane. The mold jaws can be brought together or moved apart on trolleys. In order to move back the mold jaws, they are first moved apart on the trolleys; then the carriage with the moved-apart mold jaws is moved back past the mold jaws of the other carriage, to the beginning of the mold section, and finally the mold jaws are again brought together on the carriage.
DE-A-43 18 514 discloses a device for the production of corrugated pipes from thermoplastic, which device has a mold section leading away from the head of an extruder consisting of a guide located in a frame on which mold jaws, closed in pairs to form annular molds in an inlet, are moved in close succession, which mold jaws are provided on their underside with, toothed, racks. In an outlet, the mold jaws are separated from one another and grasped by gripping arms provided with coupling devices and are inserted by them, once again, into the inlet of the mold section. The gripping arms are supported by drives that are movable on carriages, which can be moved by drives back and forth on guides to and from return sections that are parallel to the mold section. In order to be able to control the gripping arms with a simple and stable structure and in a simple manner, they can be moved in guides of the carriage exclusively transverse to their path of movement.
DE-A-43 38 990 discloses a device for the production of corrugated pipes from thermoplastic, which device has a mold section leading away from an extruder head that consists of a guide located in a frame on which mold jaws, closed in pairs to form annular molds in an inlet, are moved in close succession, which mold jaws are provided on their underside with toothed racks. Drives, which mesh with the toothed racks of the mold jaws, moved together, are placed in the beginning area of the mold section. In an outlet following the mold section, the mold jaws are separated from one another and then are conducted back to the inlet of the mold section via conveyors.
EP-A-0 007 556 discloses a device for the production of pipes from thermoplastic with transverse profiling, which device has mold jaws, in pairs, conducted in a cycle on a mold section. So as to need only the smallest possible total number of mold jaws conducted, in the cycle, a carriage is provided with a swiveling arm on whose free end a coupling element for the detachable coupling to a mold jaw is located.
EP-A-1 243 400 discloses a device for the production of pipes from thermoplastic with transverse profiling, which device has mold jaws, in pairs, conducted in a cycle on a mold section. The return conveying device consists of a portal robot, which moves out the mold jaws from the mold section, returns them to the upstream end of the mold section and again moves them into the mold section. The attachment to the respective mold jaw which is moving in front, however, is brought about by pneumatic cylinders working separately from the portal robot, as a component of the return conveying device.
EP-B-0 636 462 discloses a device for the production of pipes from thermoplastic with transverse profiling, which device has mold jackets, in pairs, conducted in a cycle on a mold section. The return conveying device is formed by a return section in which a large number of drive pinions are provided, which mesh into the mold jaws from below. For the movement out of the mold section, on the downstream end, and for the movement into the mold section on the upstream end, an outlet and an inlet assembly are provided as a component of the return section, wherein the transverse conveyance of the mold jaws takes place by means of pinions driven in a transverse movement. These transverse conveying pinions drive the mold jaw to be conveyed, on the one hand, in the production direction. On the other hand, the transverse conveying pinions are supported on spline shafts in a way so that they can be displaced axially; thus the transverse conveying pinions can also be driven in their axial direction, in order to move the mold jaw to be conveyed into and out of the mold section.